Apparatus for heating fluids



Aug. 9, 1949.

APPARATUS FOR HEATING FLUIDS Filed Oct. 30, 1944 H. P. DAYTN ETAL 5sheets-sheet 1 INVENTORAS.

ATTORNEY.

Aug. 9, 1949. H. P.- DAYToN ErAL 2,478,686

y 'APPARATUS FOR HEATING FLUIDS med oct. so, 1944A s sheets-sheet 2WNVENroRs.

ATTORNEY.

Aug. 9, 1949. P. DAYTON ETAL APPARATUS FOR HEATING FLUIDS 5 Sheets-Sheet5 Filed Oct. 30, 1944 wv IN VEN TORS.

AU- 9, 1949. H. P. DAYToN ET Al. 2,478,686

APPARATUS FOR HEATING FLUIDS Fired oct. 30. 1944 5 sheets-sheet 4 FIG.5A. as 24 Q Q.: Q Q. Q. Q

Aug. 9, 1949. H. P. DAYTON ET AL 2,478,686

v 'APPARATUS Fon HEATING mums Filed oct. so, 1944 5 sheets-sheet 5 A BYFlG. s. 'lr.. A ENT.

Patented Aug. 9, 1949 APPARATUS FOR HEATING FLUIDS Herbert P. Dayton,Baytown, and Conrad ILKolienberg, Goose Creek, Tex., assignors toStandard Oil Development Company, a corporation of Delaware ApplicationOctober 30, 1944, Serial No. 560,964 9 claims'. (c1. 12a- 250) Thepresent invention is directed to an apparatus suitable for heatingfluids, and more particularly to a heater adapted for heatinghydrocarbon oils containing finely divided solid in suspension therein.

The device of the present invention is particularly suitable forcracking petroleum oils while using the suspensoid technique, wherein afinely divided catalyst is suspended in the oil and the suspension thenforced through a heating coil. It is often desirable to conduct thecracking operation wth the oil in a vapor phase, and if the conduitthrough which the oil is forced to flow contains abrupt turns, there isa decided tendency for the solid material to be thrown to the outside ofthe turn by centrifugal force, with resultant rapid erosion of theapparatus at the turns. By employing the apparatus of the presentinvention, higher concentration oi' iinely divided solid catalyst may beemployed (with resulting improved cracking) than in the usualreturn-bend type of coil,since the erosive action is distributed withdesirable results over the entire coil rather than in the sharpreturn-bends.

The device of the present invention may be briefiy described asinvolving a coll through which the material to be heated is caused toflow. The coil comprises a number of sections having the ends joinedtogether in such a way that they may be readily connected ordisconnected. while the furnace is provided with means arranged toshield the points of connection of the sections from the direct actionof the combustion gases in tbe furnace used for heating the coil. Thecoil is arranged in the furnace so that the portion of the coil subjectto the more severe eroding action of the suspensoid is heated to ahigher temperature than the remainder of the coil, In those portions ofthe coil subjected to the highest temperatures. coke or carbonaceoussolid material is more likely to form and the eroding effect of thefinely divided solid is utilized to rernove the coke or carbonaceousmaterial from the coil.

Other obiects and advantages of the present invention may be seen fromthe following description taken with the drawing, in which:

Fig. 1 -is an elevation partly in section of an embodiment of thepresent invention;

Fig. 2 is a View yalong line II-II of Fig. 1;

Fig. 3 is an elevation of another embodiment of the present invention;

Fig. 4 is a section taken along IV-IV oi' Fig. 3:

Fig. 5 is a top view, with parts cut away, of

another embodiment of the present invention.

. another embodiment of the present invention.

2 The embodiment of FIg..5 is generally similar in elevation to theembodiment of Figs. 1 and 2.

Figure 5A is an elevation partly in section of the embodiment of Figure5.

Fig. 6 is a top view, with yparts cut away, of

The embodiment of Fig. 6 is generally similar to that of the embodimentof Figs. 1 and 2.

` Figure 6A is an elevation partlyin section of the embodiment of Figure6.

Figure 7 is an elevation partly in section of a still further embodimentof the present invention; and

Figure 8 is a view taken along line V-V of Figure 7. I

In the description of the several figures of the drawing, correspondingnumerals will be -em'- ployed to designate corresponding parts.

Turning now specifically to the drawing. and first to Fig. 1, afoundation I I is arranged to supportr a furnace wall I2 having agenerally cylindrical shape and formed of a suitable refractorymaterial. Concentrically arranged within wall I2 is a second wall I3,having a generally cylindrical shape and spaced a substantial distancewithin wall I2 to define an annulus I4, which serves as a passage forthe combustion gases of the furnace. A helical coil I5, made up of aplurality of sections I6, with each section bent through an angle of 180and the ends of the sections secured together by flanges I1 to formfluidtight joints, is arranged around the inner furnace wall I3 and issupported thereby. The furnace is provided with a floor I 9 constructedof' a suitable refractory material. The floor is pierced by a pluralityof ports 20, with a burner 2I arranged in each port and a conduit 22arranged to supply each burner with a suitable combustion mixture. Theburners are directed upwardly to allow the direction of flow of thecombustion gases to be substantially parallel with the longitudinalvaxis of the coil I 5 as well as with the walls I2 and I3. The annulusI4 discharges into an upper zone 23, defined by shell 24. Shell 24 isarranged to direct the hot gases through a preheating zone 25,containing tubes 26, and subseouently discharges the gases into stack21.

While the inner furnace wall I3 has been described as having a generallycylindrical shape,

the wall departs slightly from such a shape in order to prevent flangesI1 from coming direct- 1y into contact with the hot combustion gasesfilling space Il. Member I3 is conveniently constructed in two arcuatesections 28 and 29, with each arcuate section extending through substan-'present invention.

tially less than 180, and the ends of arcuate section 28 joined tostraight wall sections 30 extending outwardly from the ends of section28 and beyond helical coil I5. Similarly, the ends of arcuate section 29are secured to straight sections 3I extending outwardly beyond helicalcoil I5. The ends of the sections 30 and 3| are joined by sections 32extending at right angles to sections 30 and 3|. l Eachwall sectioncomprising units 30, 3| and 32 may be said to form an outset section toshield flanges I1 from the combustion gases. It will be understood thatwalls 30 and 3| are pierced by a plurality of ports or openings to allowthe passage of the turns of helical coil I through said walls.

'I'he two outset sections comprising walls 30, 3| and 32 and spacedapproximately 180 apart serve as the supporting means for coil I5. Inthe drawing the walls are shown as constructed of refractory materialand pierced by poits through which the coil extends with each turn ofthe coil resting directly on the refractory of which these outsetportions of the wall are formed. It will be understood that, if desired,metallic hangers may be used to suspend the coil from wall I3 and theports in the outset portions may be made substantially larger than theoutside diameter of the coil, with the space between the openings in theoutset portion of the wall and the coil filled by a suitable plugging orcalking matcrial to prevent direct contact of the hot gases from spaceI4 with the flanges Il.

In suspensoid cracking operations it is conventional to vaporize ahydrocarbon feed stock and admix finely divided solid therewith to forma suspension, and pass the suspension through a heating coil. In thedrawing either liquid or vaporized hydrocarbon containing the finelydivided solid catalyst may be passed via inlet 33 into the lower end ofcoil I5, caused to flow in a continuous manner through the coil andremoved from the upper end thereof via outlet line 34. It will beunderstood that the apparatus employed for preheating the oil and forforming a mixture of suspensoid in the vaporized oil is conventional tothe art, suitable apparatus being disclosed, for example in U. S.Patents No. 2,319,710 and No. 2,322,070, issued to R. K. Stratford andR. H. Smith on May 18, 1943, and June 15, 1943, and accordingly suchapparatus is not shown in the description of the furnace of theSimilarly, the subsequent treatment of the mixture of thermally treatedoil and suspensoid is conventional to the art and is not shown in thedrawing.

When it is desired to disconnect the several sections comprising theheating coil, flanges I1 may be disconnected and the coils movedoutwardly into space I4 until the ends thereof are free from walls and3|. It is preferable to employ as coupling means I1 flanges which may beremoved from the ends of the coil so that the ends of the coil may passthrough openings of substantially no greater size than those throughwhich the sections of the coil pass when the coil is intact. If suchremovable anges are employed, it will be necessary to disturb therefractory material very little, if at all, in order to dismantle thecoil I5. However, if desired, the flange members may be fasteneddirectly to section i5 and portions of the refractory material removedfrom walls 30 and 3| to allow the passage of the flange memberstherethrough in dismantling the helical coil, and upon reassembling thecoil such openings may be filled with refractory material.

It will be evident that the outside portion of coil I5 receives asubstantially greater amount of heat than the inside portion because ofthe exposure of the outside portion to the radiant energy received fromthe combustion mixture. In cracking operations, coke and carbonaceusmaterial result at the high temperatures to which the hydrocarbonmaterial being cracked is exposed. and such materials are deposited to agreater extent in those portions of the apparatus subjected to thehigher temperatures. When employing the furnace of the present inventionfor cracking oils there will be a tendency for substantially greaterportions of coke and carbonaceous solids to deposit on the outer ratherthan on the inner side of the interior surface of the coil. The solidmaterial conventionally employed in cracking operations has a densitymany times greater than the vaporized hydrocarbon preferably employed asthe suspending medium, and the ilow of the suspensoid through the coilcauses a centrifugal force to be exerted on the solid material whichforces it to the outside of the helical coil. Accordingly, that portionof the coil in which there is a greater tendency to form coke issubjected to a greater erosive effect from the suspensoid than is theremainder of the coil, and the scouring effect produced by the solidmaterial as it passes through the coil is. at least in a substantialmeasure, proportioned to the tendency of coke to deposit on the surfaceof the heating coil.

It is to be understood that the present invention is not limited to theuse of any specific dimensions in the construction of the device nor tothe thermal treatment of any specific charging stock nor to any specificcharging rate. It will be found, for example, that the diameter of thecoil may be varied from less than 20 to greater than feet, as desired.It will also be found that the furnace may be employed for thermallytreating a substantial range of hydrocaribons at any desired chargingrate. It is preferred, however. to employ a hydrocarbon in the gas oilboiling range as a charging stock and to pass the suspension of vaporsand catalyst through the coil at a rate in the order of to 200 feet persecond.

Although 'for purposes of description the apparatus has been describedas circular in cross section. it is to be understood that the exteriorwall of the apparatus may be square or even rectangular in shape.Preferably, however, the outer wall should be substantially parallel tothe curvature of the heating coil, since the greater part of the heatimparted to the fluid flowing in the coil is obtained by radiation fromthe llame and from the outside refractory wall.

The embodiment of Figs. 3 and 4 may be similar to that of Figs. 1 and 2in the arrangement of the foundation and floor. The coil I5 is made upof sections, with each section defining an arc of approximately and theends of the sections secured together by flange members I1 in exactlythe same way as the embodiment of Figs. 1 and 2.

The outer wail in the embodiment of Fig. 3 is comprised of arcuatesections 35 and 35, with each section deiining an arc somewhat less than180. The inner wall is comprised of sections 2B and 29 extending throughan angle of somewhat less than 180 and corresponding to the sectionsdesignated 'by the identical numbers in the embodiment of Figs. 1 and 2.Adjacent ends of sections 28 and 35 are connected by the straight wallsections 31-31, and the adjacent ends of sections 38 denne a secondcombustion zone.

dened by combustion zone |4 of the embodiment shown in Figs'. land 2. Inthe embodiment of Fig. 3, burners 2|' are arranged' in each combustionzone I4' with the combustion gases directed substantially parallel tothe longitudinal axis of coil I5. The upper ends of the combustion zonesI4'-|4' discharge into a shell 24'.,.

which defines a preheating section 25 containing coils 26 and dischargesinto stack 21. Y

The embodiment of Figs. 3 and 4 conveniently allows the circulation ofair adjacent the flange members |1 so that these members may be at atemperature substantially below the temperature of the refractory wallswithin combustion zones |4-|4'. In this embodiment the flange membersmay be inspected while the furnace is in operation and maintenance andrepair operations may be carried out on this part of the apparatusbefore the entire furnace has been cooled. It will be understood thatthe flanges I1 of the embodiment of Figs. 3 and 4 may either beremovable to allow the convenient removal of the Vends of coil sectionI6 through walls 31 and 38,

or alternatively flange member |1 maybe secured to the ends of sectionI6 in a more permanent manner and the openings in walls 31 and 38through which coil sections I'6 pass may be enlarged to allow thepassage of the flange mem- I 'bers when vremoving or replacing sectionI6 of the coil.

Another embodiment of the present invention is shown in Fig. 5. Fig. 5is a top view, with parts cut away, to give a view generally similar tothe top View shown in Fig. 2 of the embodiment illustrated in Figs. 1and 2.

In Fig. 5 a heating coil 40 is made up of 60. sections with six sectionsmaking up a complete turn of the coil. The ends of the sections areconnected together by flanges 4|. The combustion zone is dened by aninner wall comprising 6 arcuate segments 42 with the ends of the arcuatesegments connected together by straight wall sections 43 and 44. Anouter tubular wall 45 is spaced a substantial distance away from theinner wall and cooperates therewith to define a combustion zone 46, inwhich burners 2| are arranged to direct combustion gases substantiallyparallel with the longitudinal axis of coil 40, as well as parallel tothe longitudinal axis of outer wall 45, and the inner wall is comprisedof sections 42, 43 and 44. It will be understood that straight wallsections 43 serve to support the segments of heating coil 40.

The embodiment of Fig. 5 is particularly adapted for large furnaceswherein the heating coil may have a diameter as great as 60 feet. Thedivision of each turn of the heating coil into at least 6 segments, withthe ends of each segment supported, allows the segments to be made indimensions which allow them to be readily handled and in additionprovide adequate support for the segments in the furnace. In Figure 5Ait will be seen that an elevation of the embodiment of Figure 5 is givenand the general arrangement of flow of the oil through line 33 and, coil40 is similar to that described with respect to Figure 1. In thisparticular embodiment the ends of the six sections making up a completeturn of the coil are enclosed by wall sections 43 and 44 which isolatenanges 4| from the combustion section 48.

It will be seen that the arcuate segments 42 and the straight wallsections 43 Aand 44 are connected to define an inner wall. The innerwall and the outer tubular wall 45 define a combustion zone 46;

' It is usually desirable to construct the heating coil .of the furnaceof the present invention with a circular cross section anda verticalaxis.

It is also usuallyr desirable to construct the inner furnace wall andthe outer furnace wall as tubular members with a generally circularshape.

If desired, however, the axis of the heating coil may be arranged at anangle to the vertical and the plan view of the coil may be in the formof a closed curve -which is not a circle. If the plan view of theheating coil is formed into a noncircular shape, it is desirable that itbe generally oval in cross section and that the largest` dimensionacross the oval be no greater than 1,1/2 times the smallest dimensionacross the oval. Fig. 6 is a top view, with parts cut away. of anotherembodiment of the present invention. The elevational View of thisembodiment would be generally similar to the elevational view of Fig. 1.It may be pointed out that the principal difference between theembodiment of Fig. 6 and that of Figs. l and 2 is that in Fig. 6 theheating coil is, yin plan view, in the form' of an oval. and nach turnis divided into 4 sections, whereas in the embodiment of Figs. land 2the heating coil is of lfl. circular section and each complete turn isdivided into 2 parts.

In Fig. 6 a heating coil 5| is shown as comprising 4 sections for everycomplete turn with flanges 52 arranged to connect the'severa'l sectionstogetherY to form a complete coil. It will be understood that in thisembodiment ofthe invention as in precedingly described embodimenta'theheating coil will preferably comprise a substantial number of completeturns. An inner wall is defined by arcuate sections 53 connectedItogether by straight'wall sections 54 and 55 arranged with the arcuatesections 53 within the heating coil and straight wall sections 54 and55.

forming outset portions to shield the connecting flanges of the heatingcoil form direct-contact with combustion gases. An ovial shape outerwall 56 is provided which follows the same general shape as coil 5| andthe inner walll of the furnace and co-operateswith the inner Wall todeflnea combustion zone. Burners 2| are arranged in the combustion zone51 to direct the vcombustion gases substantially parallel to thevertical axis of the heating coil 5| and the inner furnace wall. InFigure 6A it will be seen that the outer oval shaped wall follows thegeneral configuration of wall 5| and the inner wall of the furnace todefine a. combustion zone 51. The inner wall is divided into arcuatesections 53 which are connected by straight wall sections 54 and 55 withthe arcuate sections 53 within the heating coil, straight wall sections54 and 55 forming outset portions to shield anges 52 'fromdirect contactwith the combustion gases in zone 51.

When the heating coil of the furnace is formed in an oval shape as inFig. 6, it is desirable for the completed coil to delinea patterncontain- The embodiment of Figures# and 8 may 'be generally similar tothat of Figures 3 and 4 with the exception that the embodiment ofFigures 'l and 8 show a structure generally oval in shape. In Figures 7and 8 the coil 60 is made up of sections with each section defining anarc somewhat less than 180. The outer wall of the embodiment of Figure'7 comprises arcuate sections 6| and 02 with each section defining anarc somewhat less than 180. The inner wall is comprised of sections 63and 64 extending at an angle.of somewhat less than 180. Adjacent ends ofsections 6I and 63 are connected by straight wall sections --65 andadjacent ends of sections 62 and 64 are connected by straight wallsections 66-$6. Sections 6|, 63, and 65 define a combustion zone 61'and, similarly, sections 62, 64, and 66 define a second combustion zone61. The two combustion zones are generally arcuate in section and aredesignated as 61-B1'. In the embodiment of Figure '1, burners 2| arearranged in each combustion zone 61' with the combustion gases directedsubstantially parallel to the longitudinal axis of wall 60. The upperends of the combustion zones S'V--Gl discharge into a shell 24 whichdefines a preheating section 25 containing coil 26 and from' thencedischarges into stack 21.

The embodiment of Figures 7 and 8, similar to the embodiment of Figures3 and 4, conveniently allows the circulation of air adjacent the flangemembers 68 so that these members may be at a temperature substantiallybelow the temperature of the refractory walls within combustion zonesi1'61'. It will be understood that, like the embodiment of Figures 3 and4, the flanges l! of Figures 'I and 8 may either be removable to allowthe convenient removal of the ends of coil 60 through walls B5 and 6B,or alternatively, flange members $8 may be secured to the ends ofsections 80 in a more permanent manner and the openings in walls 65 and88 through which coil sections 60 are passed may be enlarged to allowthe passage of the flange members when removing or replacing sections ofthe coil.

Although for purposes of description the apparatus has been described ascircular in cross section, it is to be understood that the exterior wallof the apparatus may be square or even rectangular in shape. Preferably.however, the outer wall should be substantially parallel to thecurvature of the heating coil, since the greater part of the heatimparted to the fluid flowing in the coil is obtained by radiation fromthe ame and from the outside refactory wall.

It will be understood that the number of sections required to be joinedtogether to make a complete turn of the heating coil may be varied overa substantial range. Usually it will be found convenient to use a numberranging from 2 to 6 sections to make a complete turn. That is to say, ifthe cross section of the heating coil is circular, the sections mayconveniently be formed to describe arcs ranging from 60 to 180 and may,of course, include arcs of 90 or 120. Similarly, if the cross section ofthe heating coil is in the shape of a closed curve, which isnon-circular. it will be found convenient to employ from 2 to 6 sectionsto make up a complete turn of the coil. In general, the larger the crosssection of the furnace, the greater will be the number of sectionsemployed to make a complete turn of the heating coil with the sectionsequally proportioned.

In the elevation of the embodiments of Figs. 1 and 3, the heating coilhas been shown as helical. While this is a preferred shape of the coil,it will 8 be understood that the coil is by no means restricted to ahelical shape, but that if desired the space between the turns of thecoil may be either greater or less than the spaces between the turns ofa helical coil.

Having fully described the present invention. what we desire to claimis: l

1. An apparatus for heating fluids comprising, in combination, aplurality of sections of tubing each defining an arc of not more thanreleasable flange means connecting together the tube sections to form acoil -comprising a plurality of turns, a first furnace wall comprisingan arcuate section with the radius of the arcuate section smaller thanthe radius of the coil and arranged concentric with the coil, a secondfurnace wall comprising an arcuate section having a substantiallygreater radius than the radius of the coil and concentric therewith,wall sections co-operating with the first and second furnace wall todefine a combustion zone excluding the flanges but including a majorportion of at least some of said tube sections, and means supplying airand fuel to the combustion zone and directing the resulting flames andhot gases in a line parallel with the axis of the coil.

2. An apparatus for heating fluids comprising, in combination, aplurality of sections of tubing each defining an arc of not more than180, removable ange members securing ends of the tubular sectionstogether to denne a coil comprising a plurality of turns, an outerfurnace wall member comprising arcuate sections having a radiussubstantially greater than the radius of the coil and concentrictherewith, an inner wall member comprising arcuate sections with aradius smaller than the radius of the coil and concentric therewith,non-arcuate sections in communication with the arcuate sections of theinner member, the arcuate and non-arcuate' members of the innerstructure co-operating with the outer structure to define a combustionzone including the major portion of the coil but excluding the flangemembers and maintaining said flange members in fluid communication withthe space-defined within the inner arcuate members, and means forintroducing a combustible mixture within the combustion zone and fordirecting resulting flames and gases in a direction parallel with theaxis of the coil.

3. An apparatus for heating fluids comprising, in combination, aplurality of tubular members each defining an arc of approximately 180,removable fiange members securing together ends of the tubular membersto form a coil comprising a plurality of turns and having a verticalaxis, an outer furnace wall member comprising a cylindrical refractorywall having a radius substantially greater than the radius of the coiland concentric with the coil, an inner wall member comprising twoarcuate portions each including less than 180 and with a radius lessthan the radius of the coil and concentric therewith, wall portionsarranged to join together the adjacent ends of the inner arcuate membersand to include in the space defined within the inner arcuate members theflange members Joining together the tubular members and means arrangedfor introducing a combustible mixture into the space included betweenthe inner and outer furnace wall members and to direct resulting flamesand hot gases in the space parallel to the longitudinal axis of thecoil.

4. An apparatus for heating fiuids comprising, in combination, aplurality of tube sections each denlng an arc of,180. removable flangemem bers securing together ends of the tube members to define a-coilwith avertical longitudinal axis, a rst and second arcuate furnace wallmember of the same radius and subtending equal arcs including less than180, said first and second arcuate members being concentric with thecoil and having a radius substantially greaterthan the radius of thecoil, a third and fourth arcuate furnace member subtending the same sizearc as the first and second furnace members but having a radius lessthan the coil and arranged concentric therewith with the ends of thethird membei; and the ends of the first member lying on a line and theends of the fourth member and the ends of the second member lying on aline, wall members connecting together the adjacent ends of the firstandthird and second and fourth members to denne two combustion zones anda third zone separating the combustion zones, the third zone includingthe flange members connecting together the tube members, and means forintroducing a combustible mixture into each of the combustion zones andfor directing the resulting names and hot gases in the combustion zoneparallel to the longitudinal axis of the coil.

5. An apparatus in accordance with claim 1 in which said coil iscircular in plan view.

6. An apparatus in accordance with claim 1 in which said heating coil isoval in plan View.

7. An apparatus for heating fluids comprising,

in combination, a plurality of sections of tubing each defining an arcnot greater than 180, releasable flange members connecting together thetube sections to form a heating coil, said heating coil having avertical axis and including a plus rality o f complete turns with eachcomplete turn in plan view being in the form of a closed curvesymmetrical with respect to the axis of the coil, a combustion zonedeiined by wall sections parallel with the axis of the coil, saidcombustion zone including at least a portion of each complete turn andexcluding all flange members, at least one of said wall sections beingarcuate, within the coil and -concentric therewith, at least an-1,698,789

other of the wall sections being arcuate, spaced said combustion zoneand for directing the resultng flames and hot combustion gases parallelto the axis of the coil.

8. An apparatus in accordance with claim 7 in which the arcuate wallmember within the coil is adjacent thereto and in which the combustiblemixture is supplied to portions of the combustion zone adjacent the wallmember spaced away from the coil.

9. An apparatus for heating iiuids comprising, in combination. aplurality of sections of tubing each defining an arc not greater thanreleasable flange members connecting together the tube sections to forma heating coil, said heating coil having a* vertical axis and includinga plurality of complete turns with each complete turn in plan View beingin the form of a closed curve symmetrical with respect to the axis ofthe coil, a combustion zone dened by wall members parallel with the axisof the coil and additional wall members also parallel with the axis ofthe coil and spaced from said wall members, said combuston zoneenclosing at least a portion of each complete turn, said additional wallmembers excluding all ange members of said tube sections from saidcombustion zone, at least one of the wall members being arcuate, outsidethe coil, spaced away from the coil and concentric therewith and meansfor supplying combustible liquid to said combustion zone and fordirecting the resulting flames and hot combustion gases parallel to theaxis of the coil.

HERBERT P. DAYTON. CONRAD H. KOLLENBERG.

40 file of this patent:

UNITED STATES PATENTS Number Name Date 558,918 Jones Apr. 21, 1896Gillican Jan. 15, 1929 2,214,711 Watts Sept. 10, 1940

